The engine is running. (Launch engine at login is ticked in the preferences.)
The keyboard shortcut triggers are active in the Global Macro Group.
I type the trigger but only the trigger characters are displayed as I type them but the expected word or phrase doesn't result from the Keyboard Maestro macro. For example in the editor I set up a macro to upon typing "kwaf" the macro would type "Keywords: American Football" [of course ignoring the quotes].
I restarted my Mac. I quit KM and relaunched it.
I suspect that this is something simple because Keyboard Maestro has always just worked.
My OS is 10.14.5 but KM-8 was working until I upgraded.